If you are running to an HD2K, I think you will need to change the output resolution using a different display. If I remember correctly when I originally researched this setup issue, the Vantage default output is 640x480, which I don't believe can be read by the HD2K. And I believe you can only change the output resolution using the OSD. Another way might be to feed the output of the Vantage into stock HD2K scaler just for the purpose of changing the output, then removing the stock scaler.
Btw, my suggestions to you are mostly motivated by self-interest as I am trying to streamline your setup process so you will be able to share your impressions of the unit with the rest of us more quickly.
Good luck and have fun.